Pressure sensitive transfer record sheet



April 12, 1960 H. s. PESA EI'AL PRESSURE SENSITIVE TRANSFER RECORD SHEET Filed Feb. 4, 1959 DISSOLVABLE souo COATING CONTAINING; OOLORING MATERIAL H LIQUID SOLVENT PRESSURE-RUPTURABLE w m$ Rm GWL E mAw T TT E A E M AH m C ms & SUPPORTING {was (PAPER) United States Patent PRESSURE SENSITIVE TRANSFER RECORD SHEET Henry S. Pesa and Lowell. Schleicher, Dayton, 'Ohio, assigners. to The National CashRegister. Company, Dayton, Ohio, a corporation of Maryland Application February 4, 1959, Serial No. 791,167

4 Claims. (Cl. 117-36) This invention relates to a pressure-sensitlve transfer record sheet, said sheet including a preferably porous supporting web, like tissue paper, having a first coating on a surface thereof, which first coating includes a profusion of minute pressure-rupturable capsules containing a liquid material which can be released by rupture of the capsules, and said first coating having applied thereover, arid in contact therewith, a normally substantially solid second coating, which is soluble in the liquid material of the capsule contents and which second coating contains coloring material. which rendered sufliciently mobile by said liquid to render the second coating and coloring material transferable.

If the novel transfer sheet. is. placed, coated side down, on a receiving sheet, such as paper, and pressure is applied to the back uncoated surface of the transfer sheet by a marking instrument, the capsules are ruptured in those areas to which. pressure is applied by the marking instrument, releasing the liquid contents thereof locally to form a paste of the second coating containing the coloring material, which paste, by the. applied pressure, which ruptures the capsules, is transferred to the receiving sheet, there to make a mark of the configuration corresponding to the areas to which pressure was applied. The supporting web, which was said to be porous in the preferable form of the invention, absorbs excess liquid which escapes from the ruptured capsules, so that the solvent effect of the released liquid will not spread sideways in the color-containing coating, thus keeping the transferred mark, or marks, definitely delineated.

In the preferred form of the invention, the coloring material is a dye, such as azo-oil-blue-black-B, which has been dissolved together witha chlorinated rubber in a suitable solvent such as diethyl-benzene, carbon-tetrachloride, dichloro-ethane, toluene, and xylene, or mixtures thereof. Suitable chlorinated rubber may be obtained in a solid powder under the name of Parlon, manufactured and sold by the Hercules Powder Company, having its principal ofiice in Wilmington, Delaware, of the United States of America. This chlorinated rubber is mixed with a sufiicient amount of solvent and coloring material to form a coating material with the necessary viscosity to enable it to be coated over the first coating of capsules. The capsule coating may be made according to the process described in United States Patent No. 2,800,457, which issued on the application of Barrett K. Green and Lowell Schleicher on July 23, 1957, and in which is disclosed a process whereby waterinsoluble materials may be microscopically encapsulated in a hydrophilic-colloid wall-forming material, the capsules so made being adapted to be applied as a dispersion to a supporting web. The capsule coating is first applied to the supporting web and dried, and, thereafter, the chlorinated rubber and accompanying coloring material is coated thereover and allowed to dry, such coatings being applied by any of the well-known coating procedures such as rolling, brushing, spraying, or spreading it out with a blade or an air-knife. A preferred embodi- The drawing shows a supporting web of paper having,

as a first coating, the pressure-rupturable capsules overlaid with the second coating of dissolvable. solid material carrying, or consisting of, coloring material.

In the preferred embodiment of the invention, a supporting sheet of tissue paper, such as that used as the supporting web in carbon transfer sheets, has applied thereto a coating of a liquid dispersion of microscopic solid-walled capsules, each capsule being pressure-rupturable, by pressures encountered in. marking and. printing, and each capsule containing a readily-evaporable solvent liquid. of the mentioned type. The capsules. are. made, as disclosed in the patent, in an aqueous medium, en masse, by the process to be described. Keeping the ingredients at 50 degrees centigrade, 20 grams of gum arabic is dissolved in 160 grams of Water, and into this is emulsified grams of diethylbenzene. A second sol is made of 20 grams of pork skin gelatin, having its. iso-,

with water, by the drop-by-drop addition thereof with constant stirring, until coacervation of the polymer material has been initiated. Coacervation is a separation out of the aqueous mixture of a colloidrich phase, which deposits on the individual droplets of diethylbenzone as seed points. The coacervation by water-dilution is continued until the desired amount of colloid material has been deposited around the droplets. At this point, the diethylbenzene droplets each are coated with a colloid-rich liquid wallof the complexes formed by interaction of the gum arabic and gelatin molecules. The re sulting aqueous dispersion of liquid-walled capsules then is cooled, to gel the gellable components of the polymer material, so that the liquid walls become solid, and the capsule walls then may be hardened so as to become substantially water-insoluble and able to withstand drying temperatures that formerly would have softened them. The hardening is brought about by treating the dispersion of solid-Walled capsules with an aqueous solution of formaldehyde, such being accomplished by pouring in about 20 grams of a 37%, by weight, solution of formaldehyde in water, adjusted to pH 9 to 11, with an accompanying adjustment in the pH of the whole dispersion to that range, the hardening taking, at least, about ten minutes. Enough water is added to or removed from the resulting capsule dispersion to obtain the desired coating viscosity, and the aqueous dispersion of capsules then may be coated on a supporting sheet of tissue paper and dried by any of the known procedures of hot gas or hot roller drying, enough of the coating being applied so as to leave a coating thickness of about .0006 of an inch. The second color-containing coating then is applied and dried. The novel transfer sheet so made, when placed coated side down upon a paper receiving sheet, will be responsive to the marks of an applied writing instrument such as a pen, a pencil, or type, and be evidenced by the rupture of the capsules in the coating next to the supporting paper. This local capsule rupturing releases the diethylbenzene solvent to form a paste with the materials of the color coating directly in contact therewith, the so-formed paste being transferred, by the same pressure which causes the rupture of the capsules, to the receiving sheet.

It will be appreciated that the novel transfer sheet is smudge-proof under ordinary handling conditions and remains so until the capsules are ruptured selectively by the selectively-applied marking pressures, whereupon a Patented A r. 12, 196.0

pastyor semi-liquid condition of the color coating is brought'into being, which causes transfer of a relatively large amount of material tojjthe receiving sheet without mudsina.

TAhumbei-fo'f solvents have been named for the capsulelcontents, but any comparable liquid-volatile solvent chlorinated rubber, itmay keep the transferred" pigment fro smudging. llffithappens" that the receiving sheet vent expelled from the capsules will leave the dye disparsed and encased'in the chlorinated rubber, and the dye will' not be subjected to smudge by any shearing forces applied thereto. There may be selectively substitute'd for the azo-oil-blue-black-B dye in whole, or in- P r any other oil-soluble dyes of proper tinctorial power, alone or in combination, such as Sudan III and Rhodamine B base, such being well-known and readily- .available ink-like dye materials.

lnaddition to using the transfer sheet with a paper copyjsheet, it may be used with non-porous sheets, such asthepolymer film-forming sheets made of celluloseacetate,"vinyl acetate, cellulose nitrate, and .copolymer materials of similar characteristics.

What is claimed is:l

1. A pressure-sensitive transfer sheet having on a surface thereof an undercoating and an overcoating, said coatings being in contact, the undercoating including a profusion of microscopic pressure-rupturable capsules, each capsule containing a liquid solvent, and the overcoating including a normally solid mixture of a marking material and a-binder, the mixture being soluble in the IS, fa non-absorbent nature, the evaporation of the sol-" solvent, the capsules and the mixture being present in such a ratio that when the transfer sheet is laid on a receiving surface, the capsules may be ruptured in selected areas, by pressure applied to the back of the transfer sheet by a marking instrument, to release enough solvent to make a paste of the marking material and binder in those areas, the pressure transferring the thus-formed marking paste to the receiving surface. 1

" from the capsules by rupture thereof when marking pressures are applied tothe back or the transfer sheet. by a marking instrument in contact with the receiving sheet, the liquid from the capsules causing a paste tora by solution of the overcoating in juxtaposition thereto so that it is easily transferred to the receiving sheet by the same pressures by which the capsules were 2. A pressure-sensitive transfer sheet, including a base web of paper having, on the surface thereof, an undercoating and an overcoating, the undercoating including a profusion of microscopic pressure-rupturable capsules; each containing a volatile liquid solvent, and the overcoating including a' solid deposit obtained by drying a liquid coating onto said undercoating, the liquid coating being a solution ofa solid'marking material and a solid binder, said dried coating being soluble in the encapsulated liquid, solvent, and said solvent being expressed ruptured.

3. The transfer sheet. of claim 1 in which the over coating is an oil-soluble dye mixed with a chlorinated rubber binder, and being formed into a paste by liquid i solvent expressed from the capsules. 7

4. The transfer sheet of claim 1 in' which the marking material is a solid pigment not soluble in the binder or encapsulated solvent. v

' KeferencesCited inthe'file of this patent UNITED STATES PATENTS re..." Ian. 10; 1956 2,800,457 Green July 23, 1957 

1. A PRESSURE-SENSITIVE TRANSFER SHEET HAVING ON A SURFACE THEREOF AN UNDERCOATING AND AN OVERCOATING, SAID COATINGS BEING IN CONTACT, THE UNDERCOATING INCLUDING A PROFUSION OF MICROSCOPIC PRESSURE-RUPTURABLE CAPSULES, EACH CAPSULE CONTAINING A LIQUID SOLVENT, AND THE OVERCOATING INCLUDING A NORMALLY SOLID MIXTURE OF A MARKING MATERIAL AND A BINDER, THE MIXTURE BEING SOLUBLE IN THE SOLVENT, THE CAPSULES AND THE MIXTURE BEING PRESENT IN SUCH A RATIO THAT WHEN THE TRANSFER SHEET IS LAID ON A RECEIVING SURFACE, THE CAPSULES MAY BE RUPTURED IN SELECTED AREAS, BY PRESSURE APPLIED TO THE BACK OF THE TRANSFER SHEET BY A MARKING INSTRUMENT, TO RELEASE ENOUGH SOLVENT TO MAKE A PASTE OF THE MARKING MATERIAL AND BINDER IN THOSE AREAS, THE PRESSURE TRANSFERRING THE THUS-FORMED MARKING PASTE TO THE RECEIVING SURFACE. 